Drawing board and tau-square combination



March 21, 1950 c. TYLER DRAWING BOARD AND T-SQUARE COMBINATION Filed May 8. 1947 MPH I IIIIIIIA.

, A INVENTOR. Mklis 722.5,

Patented Mar. 21, 1950 -jfuNiTED STATES. PATENT" OFFICE 1 DRAWING BOARD AND T-SQUARE COMBINATION 1 chimes Tyler, Long Beach, Calif.

- v 8Claims.

= This-invention relates to a drawing board and r-square combination in which is embodied means for so guiding the T -square on the drawing board'that the weight thereof or other slight pressure, such as the weight of the operators hand willmaintain it in perfect, uninterrupted alignment with the board and for locking the T-square in any desired position of adjustment of the board against movement in any direction.

' "The conventional type ofT-square consists of a. rectangular head to which a blade is secured in any suitable manner. When such square is applied to an ordinary drawing board, it is found that the head thereof overhangs one side edge of-the board and that because so exposed it is difficult to-maintain the T-square in the correct position on the board because any slight inad- Application May 8, 1947, Serial No. 746,733

vertent movement of the hand or arm is sufficient I guided on the board and so that any pressure applied thereto will tend to maintain it more firmly in any desired position on the board.

It-is' a further object to provide a combination of the character referred to wherein the T-square may be' bound or tied to the board in' such a fashion that it cannot be lifted away therefrom but so that it will still be perfectly guided and free to move longitudinally within the groove of the board. I: A still? further object is to provide a T-square combination'whichi'may be manually operated to lock the T-square rigidly in any position of adjustmen't on the board;

Still another object is to provide a combination in which the'bla'de of the T-square at and near the point where it is fastened to the head, is held elevated a slight distance above the surface of-the drawing board in order that it may not rub against the surface of the drawing paper fastened on the drawing board while it is bein moved backand forth along the groove of the board. 1.; ..i i --These and other objects as well as the many advantageous features of the. invention will be better understood from the following detailed description. and byreferring to the drawings which are hereto-annexed and in; which a. preferred form of the inventionis'illustrated.

In the drawings:

Fig. l is a plan view of a device embodying the invention; 1 f

Fig. 2 is a corresponding end view of the device partly in cross section; and

Figs. 3 and 4 illustrate details of construction, the importance of which is hereinafter fully ex-v plained.

The drawing board I may be of any conventional size and proportion and it is made near one side edge thereof. with a groove having a fiat bottom 2 and the outer edge 3 thereof is shown inclined about 27 degrees from the vertical. The upper halfportion of the inner edge 4 thereof on the other hand is vertically directed and the lower half portion 5 thereof is inclined about 27 degrees in the opposite direction from that of the outer edge 3. The edges of the head 6 are correspondingly shaped in order that the head may be snugly fitted within the groove and yet be capable of longitudinal movement therein. It is important to note, however, that the bottom surface 1 of the head is, elevated a short distance above the bottom surface 2 of the groove for reasons which will be explained presently.

In shaping the head of the T-square it is important to make certain that the upper surface thereof is slightly elevated above the surface of the drawing board or, if preferred, that a thin spacer or shim 9 may be placed between the blade and the headof the T-square. When the blade is in such manner held elevated, it is noticed that it does not come into contact with the drawing board a distance from the groove far enough to eliminate any possibility of the blade rubbing against the drawing paper on the board, along this elevated portion thereof. The upper surface of the T-square head or of the shim 9 thereof, may be slightly inclined substantially as indicated in Fig. 2 in order that the outer end of the blade beyond this elevated portion thereof may rest on the paper. Where the blade is somewhat flexible, no such inclination is necessary. When the parts are shaped and arranged as above described,it is found that the T-square will remain firmly seated in perfect alignment with the board without thought of exerting pressure thereagainst. p

It was above stated that the upper portion} of the inner edge of the groove is madeper pendicular to the bottom surface of the groove and that the lower portion 5 is inclined a distance of about 27 degrees. Other grooved drawing boards have been made having-inclined side edges but in such devices as have come to my attention 3 it has been found that both side edges of the groove have been symmetrically inclined. When so shaped it is found that inward pressure on the outer edge of the blade tends to dislodge the head from the groove and so to disturb the setting of the T-square, but where the upper portion 4 of the inner groove is made perpendicular, as herein shown, it is found that. such pressure against the end of the blade tends if anything more firmly to seat the blade in the groove.

Where the T-square head is snugly fitted within the groove of the drawing board, as in the device of the present invention, it may be found rather. difficult to dislodge the head therefrom and that it may be found necessary to slide the head to one end of the groove in order to get a firm grip thereon. In order to render the T-square easy and convenient to remove from the groove, I have bevelled the bottom edge of the overhanging endof the blade substantially as indicated at 10 r in Fig. 2, the angle inclination being in this case about 10 degrees. When the bottom edge of the blade is in this manner bevelled, it is merely a matter of applying a light downward pressure to the outer end of the blade in order to tilt the head of the T-square to release it for removal out of the groove. The operation of the device is in such manner greatly improved.

While in the device, as above described, the

T -square is held snugly in position within the groove, it may at times be found convenient to tie it to the board in such a fashion that it will still be slidable therein but in which position it will be impossible to raise it out of the groove. Such tying of the T-square to the board may be effected by mounting a plate H on the underside of the T-square head by means of a stem [2 which extends vertically through the head and is at the top fitted with a hand-lever E3. The plate H is so shaped that it may be rotated to engage a recess I4 at the bottom of the outer edge 3 of the groove. It is noticed that the plate is made with a raised portion IS in axial "alignment with the handle l3, which portion,

when the handle is in the central position indicated in Fig. 2, acts as a cam engaging the upper surface of the recess 14 to lock the T-square against sliding movement within the groove. When the handle is moved to the intermediate position of Fig. 1, it is found that the head 6 may be moved along the groove but cannot be lifted out of it.

It was above stated that the head of the T-square is shaped to fit snugly within the groove of the board and attention was directed to the advantage of the vertical side wall portion 4, which serves as a means of anchoring the T- square more firmly within the groove. It was also stated that the head 6 is similarly shaped and that it fits the groove snugly. Another advantage of this arrangement is that the T-square may be removed from the groove and applied to the outer edge of the board or to the edge of any drawing board, thevertical surface I! thereof forming a perfect guide therefor.

The T-square of my invention is in this manner made more universal in its adaptation and the drawing board may be turned upside down to enable the draftsman to make use of both sides of the boards, if found necessary.

In order to facilitate setting the cam, I have placed on top of the blade a scale It having graduations indicating the extent to which the handle 13 is rotated in order to turn the plate to an intermediate position in which to maintain the T-square slidable within the groove and further rotated to clamp it against longitudinal movement therein. But I wish it understood that the devices just describedare merely illustrative of means for controlling the movement of the T-square on the board and that other means may be substituted, if preferred.

The drawings are merely illustrative of means for carrying the principle of the invention into practice and I reserve the right to embody there- ..in such modifications as will come within the scope of the claims hereto appended.

It is seen from the foregoing description that I have provided a simple and inexpensive combination in which the T-sq'uare at all times remains snugly seated without; exertion of pressure wherein the T-square'rnay be so bound or tied to the board that it is movable therealong but cannot be vertically removed therefrom; and wherein the square may be locked in any desired position on the board. It.is also important to note that the shape of the groove and of the head operable therein adapts the T-square for *use on any one of the outer edges of the board,

on both sides thereof. It may for this reason fittingly be termed a dual purpose T-square.

Iclaim:

1. In combination with a=drawing board having a groove sunk into the surface thereof parallel with one side edge of the board, a T-square comprising a head shaped to fit said groove and a blade fastened to the top of said head, the body portion of said blade extending across the surface of the board, the blade extending beyond the head substantially to the edge of the board adjacent said groove, the bottom surface of said extending portion of the blade being upwardly inclined toward" the end thereof, pressure against said extending portion of the blade causing the head to rock in the groove thereby to elevate the body portion of the blade above the surface of the board.

2. In combination with a drawing board having a groove sunk into'the surface thereof parallel with one side 'edge of the board, a T-square comprising a head shaped to fit said groove and a blade fastened to the top of said head, the bottom surface of said'head being elevated above the bottom surface of said groove, the body portion of said blade extending across the surface of the board, the blade extending beyond the head substantially to the edge of the board adjacent said groove, the bottom surface of said extending portion of the blade being upwardly inclined toward the end thereof, pressure against said extending portion of the blade causing the head to rock in the groove thereby to elevate the body portion of the blade above the surface of the board.

3. In combination, a drawing board having a groove in the upper surface thereof adjacent one side edge of the board, the side of said groove adjacent the said edge of the board being upwardly inclined toward the side edge, the upper half-portion of the opposite side of the groove being perpendicular to'the top surface of the board, the lower half-portion thereof being inclined in the opposite direction relative to the incline of the other side edge, theinclined surface nearer the side edge of the board being undercut, a, T-square having a head slidable in said groove a cam plate on the head positioned between the bottom surface thereof and the bottom surface of said groove and means rising from the top of the head and manually movable to cause the said cm to engage the said undercut portion of the board groove.

4. In a device of the character described, a drawing board having a groove in the surface thereof adjacent one side edge thereof, the side surface of said groove nearer the said side edge being upwardly inclined toward the latter, the opposite side edge of the groove extending vertically downward for a distance and continuing to the bottom of the groove on an inclination in the direction opposite to that of the first named inclined side surface of the groove, the latter bethe undercut portion of the groove.

5. In a device of the character described, a

drawing board having a groove in the surface thereof adjacent one side edge thereof, the side surface of said groove nearer the said side edge being upwardly inclined toward the latter, the opposite side edge of the groove extending vertically downward for a distance and continuing to the bottom of the groove on an inclination in the direction opposite to that of the first named inclined side surface of the groove, the latter being undercut to form a recess in continued alignment with the bottom of the groove, a T-square having a head shaped to ride in the groove, the lower surface of said head being elevated above the bottom surface of the groove, a stem vertically extending through the head, a cam on the lower end of said stem positioned within the space between the head and the bottom of the groove, means at the top of said stem operable to rotate the stem thereby to move the said cam into the undercut portion of the groove, and a scale on the head indicating the positions taken by the cam.

6. A T-square having a head and a blade transversely mounted thereon, the outer side edge of the head being downwardly bevelled, the upper portion of the inner side edge of the head being perpendicular to the top surface thereof, the lower portion of the inner side edge being similarly inclined in the direction opposite to that of the other side surface, the blade extending a distance beyond the said outer side edge of thehead, the bottom surface of said extending portion of the blade being upwardly inclined.

7. A T-square having a head and a blade transversely mounted thereon, the outer side edge of the head being downwardly bevelled, the upper portion of the inner side edge of the head being perpendicular to the top surface thereof, the lower portion of the inner side edge being similarly inclined in the direction opposite tothat of the other side surface, the blade extending a distance beyond the said outer side edge of the head, the bottom surface of said extending portion of the blade being upwardly inclined, and

a shim mounted between the head and the blade. 8. A T-square having a head and a blade transversely mounted thereon, the outer side edge of the head being downwardly bevelled, the upper portion of the inner side edge of the head being perpendicular to the top surface thereof, the lower portion of the inner side edge being similarly inclined in the direction opposite to that of the other side surface, the blade extending a distance beyond thesaid outer side edge of the head, the bottom surface of said extending portion of the blade being upwardl inclined, the upper surface of the head being slightly inwardly inclined.

CHAS. TYLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 329,392 Jordan Oct. 27, 1885 817,991 Ross Apr. 17, 1906 1,746,830 Harmon "Feb. 11, 1930 2,089,757 Nieukamp Aug. 10, 1937 2,424,840 Murphy July 29, 1947 FOREIGN PATENTS Number Country Date 3,290 Great Britain 1 1886 105,711 Sweden Oct. 13, 1940 353,074 Great Britain July 23, 1931 

